1. Field of the Invention
The present invention is directed to providing a sealable connecting device for coupling one component onto a rigid tubular terminal portion of another component and, more specifically, to such a connecting device in which the components to be coupled are of the male-female type.
2. Description of the Prior Art
It is not uncommon, in various machines, devices, or systems, to employ flexible tubes, which are formed of thermoplastic or elastomer materials which are sometimes reinforced with textile reinforcements. The increasing use of such flexible tubes have given rise to a large number of quick-connection systems, which may be detachable or semi-reusable. Two major categories of such systems can be found in the prior art.
The first category includes a generally symmetrical system, in which a gasket is axially compressed by two components which may, for example, be locked together by a rotating bayonet device. The most common examples of such systems include hoses for fire trucks and compressed air feed lines used in industry and in public works. In such connecting or coupling devices, the sealed joint may or may not be subjected to slight deformations in a direction perpendicular to the principal direction of compression during the locking process.
On the other hand, another category of connecting or coupling devices employ male-female elements, which are, in most cases, two cylindrical or essentially cylindrical elements for being disposed on the same axis during the coupling. The axial movement required during the coupling is linear and, with few exceptions, the preferred seal between the male-female element includes a round gasket, an O-ring, or a flanged ring. In order to oppose the pressure of the fluid transported through the connecting device, the compression of the gasket or ring is essentially radial and, therefore, can only be produced by sliding over one of the rigid surfaces. Quite frequently, in a so-called "O-ring" coupling in which an O-ring is supported by the male terminal or element, the surface providing the seal must be of an appropriate nature to slide over the O-ring which is on a cylinder which surrounds the area of fluid flow. Such an O-ring device requiring a sliding action during coupling is disclosed in U.S. Pat. No. 4,193,616 (DANA CORP), although the patent is primarily directed to a locking coupling and not to the particular sealing zone disclosed therein.
In such prior art devices, the mechanical coupling between the male and female elements is often achieved either by means of a threaded coupling, by the engagement of levers which rock in a plane passing through the axis, or by other means, including semi-recoverable clamping. Examples of typical mechanical couplings are disclosed in French Pat. Nos. 2 558 563 and 2 585 443 (RASMUSSEN) or European Pat. No. 031 409 (ARMATURENFABRIK HERMANN VOSS).
Some of the devices disclosed in the patents mentioned hereinabove differ in the particular manner in which the flexible tube is fastened to one of the terminals. One discloses a vulcanized connection. Two other patents disclose devices which employ radial mechanical clamping, one of which is by expansion of an internal rod and the other of which is by external clamping. Generally, the prior art devices do not include both a means for irreversibly fastening a flexible tube to a terminal and a means for providing a secure seal in a system which is simply to provide and easy to assembly.
With regard to a method and means of irreversibly fastening the flexible tube to the male terminal, the application of such a process is described in French Pat. No. 2 596 133. A device to connect a flexible pipeline to a rigid tube by means of a collar due to the contraction of an external polymer covering is disclosed therein, in which, in one embodiment, the terminal is effectively detachable, and can be used in the present invention.
There remains a need for any device which can be employed to improve the reliability and security of the type of seal produced by elastomer O-rings in the devices of the prior art. In such prior art devices, some of the O-rings must slide over a rigid surface, while being subjected, by means of a bevel, to a radial stress which is required to ensure the seal. Since, because of customary safety coefficients, the surface pressure exerted in operation at the contact surfaces of the joint is approximately three times the nominal pressure in the pipeline, the contact surfaces must be sufficiently smooth to allow non-destructive sliding at a relatively high pressure. The absence of fluid or lubricant during assembly very often results in the seals being non-reusable and can also lead to the destruction of the surfaces with which they come in contact.